Thursday, September 08, 2016

There for a couple weeks with my wife and nephew. No volunteering this time to pretend the travel emissions aren't sinful, just a vacation. Can't do it without some blogthoughts though!

Iceland has nearly 100%, renewable energy-sourced electricity, mostly hydro and a large chunk of geothermal, so no variability problems either. Wiki says they can do a lot more of both, although new projects attract a lot of environmental controversy. They also make extensive use of district heating as is done in a lot of Europe, and something we Americans really should take up a lot more. A lot of the home hot water is geothermal even, so very enviro if a little smelly.

Here in California there's a concern with toxic metals brought from the subsurface with geothermal power. We toured one plant and I asked about that, and the company rep said no problem there. I'm not quite clear why. It might be it's so hot there that they can pump up steam, do a heat exchange with freshwater, use the freshwater for district heating and send the steam back underground. Or maybe there's just a heck of a lot more water in Iceland than in California, so the toxics don't concentrate. Beyond my lazy tourist-sleuthing to quite nail down.

Wind energy barely exists in Iceland, and it is hard to compete with hydro on price. OTOH, habitat and cultural concerns may limit new hydro, while wind keeps dropping in price and is perfectly matched with hydro and geothermal for dependable, carbon-free power. There's even talk of exporting power to the UK, although that seems like just talk and nothing more for several years now.

I was surprised at how little EV penetration exists. Islands tend to be good markets for EVs, and Iceland has cheap electricity along with the other reasons like expensive fuel and limited driving range. Maybe the island is a little big and underpopulated with charging stations, but that should change.

Icelanders have a weird thing with trees, clearly planting them in lots of places for obscure reasons beyond wind breaks. My psychoanalysis is it's a cultural thing with two reasons: they're still traumatized by the decimation of birchwoods that originally covered Iceland, a bad decision that was only somewhat less disastrous than at Easter Island. The other reason is they want to show they can grow trees like other countries, dammit. Iceland's Forestry Department has other reasons, so take your pick.

26 comments:

I have been dreaming of doing forestry in Iceland or southern Greenland. Its the thing to do if you are interested in some future for mankind, for we need to do massive carbon sequestration. Interesting number from loc. link: "Carbon sequestration in forests planted after 1990: 200 000 tonnes CO2 per year"

Could be 10x as much for the rest of the century. Should be combined with char coal soil amendment (aka terra preta).

I can't tell for California (Geysers field is in California, right ?), but in Europe for heating (and for Soultz producing electricity) geothermy you usually pump hot brine from saline aquifers deep below the surface ; since this kind of water is not well suited with usual domestic plumbing systems, you indeed have a heat exchanger and then you inject back the brine into the same aquifer. You therefore don't have any problem with toxic metals as they are sent back where they were first (unless you have faulty wells, but this is another topic for risk management).I strongly suspect that indeed Iceland plants run the same way - the water they pump must be heavily contaminated with volcanic products such as H2S.

California in contrast is an accertionary terrane, a pile containing many metal-rich wedges of ancient seafloor scraped together at an active subductive margin, including the richest mercury deposits in North America and lots of arsenic and selenium rich gold deposits.

The result is that California's many hot geothermal springs release more mercury than US coal burning. a hazard geothermal wells can fortunately be sited to largely reduce or avoid.

The geysers produces from the Franciscan melange, which is where the new Almaden mine is situated. An accretionary wedge is a turd-skimmer on a subduction zone, scraping all sorts of odd-ball crap off the top. Dry steam paydirt is in a silicic greywacke below a very hard chert that chews up HTC bits in less than 12-hours, a pebble-pimp's dream. As I recall, mercury was generally used as a geochemical indicator from hot-spring samples for geothermal prospecting in California in the early 1980's. OTOH, a mid-ocean ridge spews thru virgin basalt

this kind of water is not well suited with usual domestic plumbing systems, you indeed have a heat exchanger and then you inject back the brine into the same aquifer. You therefore don't have any problem with toxic metals as they are sent back where they were first (unless you have faulty wells, but this is another topic for risk management)

I understand there's serious potential for geothermal in British Columbia and Alberta, too-- but it seems to be difficult to re-direct the attention of those bent on developing more familiar sources (dreams of LNG exports and the Site C hydro dam). Familiarity contributes to confidence (sometimes justifiably), but we need to get a lot more serious about investigating and expanding our options.

Figure 6.16. Average power of sunshine falling on a horizontal surface in selected locations in Europe, North America, and Africa.

Solar panels are usually tilted to be normal to the sun's path. Insolation normal to the sun is pretty much the same everywhere on the planet. It's just one of the things I find problematic with MacKay.

Average annual insolation is greatest at the equator and diminishes with latitude because seasonality. So solar arrays potentially generate more electricity per annum the closer they are to the equator. Can we agree on this?

As for the angle of a panel, the difference between horizontal and angled (and optimally situated) panels is about 10% which isn't exactly a game-changer.

I suggest that one looks at figure 2.8. I core the following paragraph,The interesting result shown by Figure 2.8 is that the yearly total solar radiation on a surface maintained normal to the sun’s rays is essentially the same regardless of the latitude. http://www.powerfromthesun.net/Book/chapter02/chapter02.html

At higher latitudes there is a greater thickness of air to travel through.

At higher latitudes there is a greater thickness of air to travel through.

You are quite right. Thanks for the correction.

This latitudinally-increasing attenuation presumably explains why panel angle of mid-latitude installations has a much smaller effect than one might expect. As an informal example, here's a UK-based SPV installer's website. From the orientation and tilt calculator table:

Average annual insolation is greatest at the equator and diminishes with latitude because seasonality. So solar arrays potentially generate more electricity per annum the closer they are to the equator. Can we agree on this?

No. Average day length is 12 hours everywhere. The difference in normal insolation at higher latitudes in the Northern hemisphere is due mostly to diffusion. Clouds and particulates and a small bit from atmospheric depth. Southern hemisphere is a different story.

All I am saying is that surface irradiance falls significantly at higher latitudes* and that therefore solar potential is greatest at lower latitudes.

Panels, be they horizontal, angled or tracking can only work with the net flux to the surface. Angling or sun tracking cannot compensate for the energy lost during the transit through the atmosphere. There is no magic bullet.

I'm not talking past anyone, just stating the facts. Facts that explain why major solar installations are built / planned / proposed for lower latitudes where irradiance is highest.

In addition to atmospheric attenuation at high latitudes, there is the matter of spacing. Sure, if you have a single solar panel, you can maximize the energy it captures by using a tracking system. But suppose you have 10,000 of them. How far apart do they need to be so that each panel can get its maximum energy without shading its neighbors?

Over a large area, you are never going to capture more energy than what falls on the ground surface. In Reykjavik, you will need about 10x the land you would need in Las Vegas to accommodate the same number of panels. And the sunlight will be about half as bright due to travel through the atmosphere. So you'd need about 20x the land and twice the number of panels to get the same amount of energy as the desert Southwest.

None of you yahoo bunnies are really grasping the magnitude of the problem. I outlined a sketch of the solution in Brian's prevacation announcement. You are arguing nits. Vast areas of desert will need to be converted to square tent arrays of rain water collecting, shade producing, energy converting surfaces, 3 meters off the ground, stake post and cable anchored into the sand, and deployed mechanically across wide swaths of ground - atomically thin photon absorbing, reflecting and transmitting surfaces with their energy conversion devices integrated into the back (down facing) side of the surface.

You are arguing the angles, while completely missing the magnitudes. The solar square arrays just provide the resources and living spaces, the real action will go on in between those squares, the alleys and pathways of intense solar illumination, where plants and trees can gain a foothold in the desert. Trees are hydrocarbon posts. What you will need to solve this problem are carbon sheets, rods and tubes, in vast quantities, that can be used to build ever more habitat in what is basically unihabitable areas of the Earth.

I'm not sure that the atmosphere attenuates the incoming radiation so much between Las Vegas and Iceland that ...the sunlight will be about half as bright due to travel through the atmosphere.

I don't know what wavelengths are predominantly useful and as I'm on a mobile device I'm not going to attempt to look it up. However, scattering is not necessarily a big issue as some PV works well with diffuse light.

Nigel, you are correct. Using the <a href="https://en.wikipedia.org/wiki/Air_mass_(solar_energy)#Solar_intensity>formulas here</a>, I get 989 W/m^2 through the atmosphere at 35N vs 785 W/m^2 at 65N, so the correct figure would be closer to 80%.

You are also correct that the attenuated wavelengths are not necessarily those most useful to PV, though I haven't found anything to indicate that the efficiency changes that much with latitude.

So I guess you'd need something more like 12.5x the land and 1.25x the number of solar panels to get the same output in Reykjavik vs the SW US.

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Eli Rabett

Eli Rabett, a not quite failed professorial techno-bunny who finally handed in the keys and retired from his wanna be research university. The students continue to be naive but great people and the administrators continue to vary day-to-day between homicidal and delusional without Eli's help. Eli notices from recent political developments that this behavior is not limited to administrators. His colleagues retain their curious inability to see the holes that they dig for themselves. Prof. Rabett is thankful that they, or at least some of them occasionally heeded his pointing out the implications of the various enthusiasms that rattle around the department and school. Ms. Rabett is thankful that Prof. Rabett occasionally heeds her pointing out that he is nuts.